This invention relates to lock cylinders for door locks.
Conventional lock cylinders comprise a single set of pins which are moved into alignment to permit cylinder rotation by the cut notches or ridges of the appropriate key.
It is also known in the prior art to provide a lock cylinder having two sets of pins spacedly disposed 180.degree., so as to accommodate a key on which notches have been cut on edges disposed 180.degree..
In prior art lock cylinders, locking pins were in abutting relationship with driver pins, and the line of abutment was disposed below the pin shear line or cylinder rotation line without key insertion. With key insertion the locking pins and driver pins were lifted by the edge of the key so that the pin line of abutment was coincident with the pin shear line thereby permitting cylinder rotation.
While such prior art lock cylinders served their intended purpose, the lock cylinders were readily subject to picking by jiggling the pins into alignment so as to permit rotation of the cylinder. This was particularly so because the picker knew to lift the locking pins until the cylinder exhibited freedom of rotational movement.
Now there is provided by the present invention a lock cylinder wherein at least one of the locking pin-diver pin sets is disposed so that the line of abutment is above (i.e., radially outwardly disposed) the pin shear line prior to the key being inserted, and with key insertion the abutment line is then brought into alignment with the pin shear line. With some pin sets so disposed, picking attempts are frustrated.
There is further provided by the present invention means to hold the aforesaid pin sets in the above shear line disposition and to insure that the holding means positively acts in the intended manner with key insertion and removal. Also in one preferred form of the invention the aforesaid holding means is contained entirely within the cylinder itself thereby permitting replacement of conventional cylinders with the present invention, insofar as the exterior appearances are similar.
There is also provided by the present invention, a lock cylinder in which there are two sets of pins with tapered ends in abutting relationship so as to frustrate attempts to jiggle the pins into rotational alignment. The second set of pins interferes with the operation of the picking devise so in effect both sets of pins must be aligned simultaneously with one picking device at their points of abutting contact.
It is a principal object of this invention to provide a lock cylinder wherein at least one locking pin-diver pin set is disposed so that the pin set abutment line is disposed above the pin shear line prior to key insertion, and the abutment line is made coincident with the shear line with key insertion.
It is another object of this invention to provide the cylinder as immediately aforesaid wherein the means to hold the above shear line disposition of the pin set is contained within a conventionally-sized lock cylinder.
It is a further object of this invention to provide for routine acting means to hold the above shear line disposition of the pins before key insertion and with key removal.
It is also an object of this invention to provide a lock cylinder in which sets of key-actuating lock pins abut each other to frustrate attempts to pick the lock.
It is another object of this invention to provide a lock cylinder as aforesaid in which the two sets of pins are angularly disposed at an angle providing the desired interference to prevent picking.
It is still a further object of this invention to provide a lock cylinder as aforesaid in which both sets of pins must be aligned to permit rotation.
It is still a further object of this invention to provide a lock cylinder as aforesaid in which the pins are mutually biased in abutting relationship.
It is still a further object of this invention to provide a lock cylinder with two abutting pin sets as aforesaid, whereupon insertion of the correct key one set of pins drops into alignment with the pin shear line whereas the other set of pins is raised by the key into alignment with the pin shear line.
It is still a further object of this invention to provide a lock cylinder as aforesaid in which a hardened face plate protects the shear line of the pins.
Another object of this invention is to provide a lock cylinder as aforesaid which is safe and practical in use and yet is readily fabricated and of relatively inexpensive construction.